Shallow focus techniques are typically used by photographers to create images in which a portion of the scene is in focus and a remainder of the scene is out of focus. For example, shallow focus techniques may bring an object in the scene into sharp focus and the more distant background out of focus. This is sometimes referred to as the bokeh effect.
To create the bokeh effect, a main object to be highlighted is positioned within the depth of field while the background is positioned out of the depth of field. The depth of field depends on a number of factors, including the aperture size and the focal length of the camera. In general, the larger the aperture of the camera, the shallower the depth of field.
Shallow depth of field may be achieved with professional cameras, such as digital single-lens reflex (DSLR) cameras. Less expensive cameras (such as cellphone cameras and small point and shoot cameras) typically have small lens apertures that cannot achieve a shallow depth of field, and may not be capable of creating the same artistic defocus effect that may be achieved with professional DSLR cameras.